There are a variety of spectroscopic tools for characterizing atomic or molecular compound. These include, but are not limited to, x-ray, UV, visible-light, infrared and microwave spectroscopy, and nuclear and electron spin resonance (NMR and ESR) spectroscopy. In general, spectroscopic tools are useful for at least four different type of chemical-analytical problems: first, to characterize an atomic and molecular compound according to its spectrographic features, e.g., spectral components; second, to determine the atomic composition of a compound, according to the spectral characteristics of atoms making up the compound; third, to determine 2-D or 3-D conformation of a molecular compound according to the spectral characteristic of atom-atom interactions in the compound; and fourth, to detect and identify components, e.g., contaminants, in a sample according to the distinguishing spectral characteristics of the compound being detected.
Most existing spectroscopic tools provide some unique advantage(s) in terms of sensitivity, the information gained, ease of measurement and cost. Because each tool provides information not otherwise available, it is generally advantageous to be able to bring to bear on any chemical-analytical, as many pertinent spectroscopic tools as possible.